I'm working on a nasty homebrew monster, and I can't help but think that I haven't balanced this thing correctly, even for a CR 30 creature. In addition to all the damage this thing can dish out in one round (a little over 300), this monster can make creatures fall prone, inflict 1 level of exhaustion, force creatures to provoke opportunity attacks with their own reactions by crawling, make creatures fall unconscious, curse creatures to lose their proficiency bonus and armor proficiencies, and even instantly kill a creature it reduces to 0 hit points with a multi-targeting attack. Most of these effects are caused by saving throws, so I ended up lowering its most prevalent DC from 23 to 19 to compensate, as some of these effects seriously hinder a creature's ability to make these saves, even though most of these effects can be undone in one round, some automatically. Is lowering the DC in this way too lenient or is it not lenient enough? The DMG suggests giving monsters extra effects when they inflict damage, but is unclear about what effect these effects can have on a challenge rating outside of those abilities in the table at the end of DMG Chapter 9.
I'm working on a nasty homebrew monster, and I can't help but think that I haven't balanced this thing correctly, even for a CR 30 creature. In addition to all the damage this thing can dish out in one round (a little over 300), this monster can make creatures fall prone, inflict 1 level of exhaustion, force creatures to provoke opportunity attacks with their own reactions by crawling, make creatures fall unconscious, curse creatures to lose their proficiency bonus and armor proficiencies, and even instantly kill a creature it reduces to 0 hit points with a multi-targeting attack. Most of these effects are caused by saving throws, so I ended up lowering its most prevalent DC from 23 to 19 to compensate, as some of these effects seriously hinder a creature's ability to make these saves, even though most of these effects can be undone in one round, some automatically. Is lowering the DC in this way too lenient or is it not lenient enough? The DMG suggests giving monsters extra effects when they inflict damage, but is unclear about what effect these effects can have on a challenge rating outside of those abilities in the table at the end of DMG Chapter 9.
Do you have a group of player who will have to fight this monster?
It sounds pretty overpowered to me, but if you have a specific group you could run the fight on your own.
Basically try if you can defeat your own monster and tweak the monster until the fight feels satisfying.
If it is just theory crafting you could still try it with a "default group". Like, Fighter, Barbarian, Paladin, Cleric, Wizard, Ranger level 20.
As far as I can tell the guidelines for monster creation are "yep, go ahead and add conditions".